The invention relates to a disc brake for a commercial vehicle having a brake caliper which straddles a brake disc, is configured as a sliding caliper, and is fastened to a stationary brake carrier. Two brake pads are arranged in the brake caliper and can be moved in opposite directions. Each brake pad has a lining carrier plate and a friction lining fastened thereon. The one brake pad on the action side can be pressed against the brake disc by way of a brake application device via at least one brake plunger.
In the case of a disc brake of the generic type, which is also known as a sliding caliper brake, an action-side brake pad is pressed against a vehicle-side brake disc in the case of a braking operation by way of a brake application device which can be actuated pneumatically or by electric motor. During the further course of the braking operation, the brake caliper is displaced, in relation to the brake disc, counter to the brake application direction of the action-side brake pad, with driving and pressing of the opposite, reaction-side brake pad onto the other side of the brake disc.
After the release of the brake, the brake caliper remains in said position in the case of the known disc brake, in which position, although the brake pads, or at least the reaction-side brake pad, bear without pressure, they bear in a rubbing manner against the brake disc. The residual rubbing moments of the brake pads which occur as a result during driving operation have a disadvantageous effect, insofar as they lead to an increased fuel consumption and to a reduction in the service life of the components involved, namely the brake disc and the brake pads.
Although a slight release of the brake pads takes place during driving operation, for example by way of tumbling of the brake disc and by way of vibrations and lateral accelerations when driving around bends, said effects are not sufficient to effectively prevent the abovementioned residual rubbing moments.
In order to counteract this problem, DE 10 2007 001 213 (which forms the generic type) discloses a disc brake having a restoring device which is arranged in one of the guide rods, via which the brake caliper is held displaceably on the brake carrier. The restoring device has a sprung restoring element, by way of which the brake caliper is displaced into a starting position.
This construction has proven itself in principle. The use of the known restoring device in the case of compressed air actuated disc brakes of heavy commercial vehicles can lead to problems, however, since broad limits of variable influences as a result of component tolerances and component deformations are in effect here, which broad limits do not permit a reliable function of the restoring device in every case.
Comparable problems result in the case of a disc brake as discussed in DE 10 2012 006 111 A1. Here, a restoring device is arranged on the side which lies opposite the brake application device and faces the reaction-side brake pad, as a result of which effective, in particular automatic restoring of the brake caliper is achieved, with the smallest possible infringement of the system rigidity at the same time.
In every case, the restoring device acts on the brake caliper, the brake carrier acting as a thrust bearing.
The invention is based on the object of developing a disc brake of the generic type in such a way that the service life, in particular, of the brake pads and the brake disc is increased and the operating costs overall are lowered by way of structurally very simple means.
This and other objects of the invention are achieved by way of a disc brake having a brake caliper which straddles a brake disc, is configured as a sliding caliper, and is fastened to a stationary brake carrier. Two brake pads are arranged in the brake caliper and can be moved in opposite directions. Each brake pad has a lining carrier plate and a friction lining fastened thereon. The one brake pad on the action side can be pressed against the brake disc by way of a brake application device via at least one brake plunger. At least one restoring device, by way of which the brake caliper can be restored after a braking-induced displacement and release of the brake, has at least two rods which bear against the brake pads in a spring-loaded manner counter to the respective brake application direction of the brake pads. One rod is configured as a pull rod and the other rod is configured as a push rod.
Restoring of both brake pads in the case of a released brake is achieved by way of the embodiment according to the invention of the disc brake. Here, the restoring force acts counter to the respective brake application direction of the two brake pads, that is to say toward the caliper back in the case of the reaction-side brake pad and toward the caliper top in the case of the actionside brake pad, with the formation of gaps with respect to the brake disc.
The action of the rods of the restoring device according to the invention on the two brake pads expediently takes place on their lining carrier plates, to be precise on the side which faces the friction lining which is fastened thereto.
In order to avoid tilting of the respective brake pad during the restoring, rods act on the brake pads, that is to say on their lining carrier plates, in each case in pairs, on the right-hand side and on the left-hand side in relation to the rotational axis of the brake disc.
The rods consist of a dimensionally stable material, preferably metal, and are of rod-shaped configuration, with a largely continuous cross-sectional dimension; largely continuous insofar as a small cuff is integrally formed on each rod, which small cuff serves as a driver in the case of the pull rod and as a stop in the case of the push rod.
The driver of the pull rod is integrally formed at its one end and bears against the action-side lining carrier plate on the side which faces the friction lining.
In contrast, the stop of the push rod corresponds with an associated spring and serves to displace the push rod in the case of relieving of the spring when the brake pads are pushed back into their starting positions in the case of a released brake.
According to one advantageous development of the invention, a rod pair, that is to say a pull rod and a push rod, are held in a housing which is arranged on or in the brake caliper, which housing can be set with respect to a vehicle-side brake carrier, on which the brake caliper is mounted axially displaceably as a sliding caliper, likewise in relation to the rotational axis of the brake disc.
It is also contemplated to assign a plurality of rods to in each case one of the springs, that is to say a plurality of pull and/or push rods.
In order to optimize the costs of the manufacture of the restoring device, identical springs are provided for the rods, for example as compression springs, in particular helical springs, with identical spring properties. The helical springs are guided on the rods, it also being possible, in particular, for the pull rod to be connected to a tension spring.
A point of action between the push rod or the pull rod and the brake pad advantageously lies in the vicinity of the resistance force which results from a supporting force between the respective brake pad and the brake carrier.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.